This invention relates to a fluid supply system for a domestic appliance and more particularly to a system for providing a predetermined amount of fluid during each cycle of operation. In applying a supply system as for example to a domestic refrigerator and more specifically to an automatic ice maker it is necessary that only the amount of fluid or water required to fill the ice molds or cavities is supplied. To accomplish this many prior art controls are employed to meter the supply of water. In many instances an electrically energized water valve is employed that is activated for a specific period of time during an ice making cycle as by a timing device or cam associated with the ice harvesting mechanism. This type of timing arrangement is satisfactory especially when used in combination with a flow control or metering system that compensates for varying pressure supply flows.
A problem, however, arises when there is a malfunction that prevents the valve from effectively shutting off the flow of water at the selected time. The malfunction can be the fault of the valve and/or its associated mechanism. It can also be a malfunction of the timer mechanism or its associated electrical components. In any event the failure of the water supply being terminated can result in substantial water damage to the surrounding environment if not remedied within a reasonable amount of time.
One approach is to employ two valves in series within one valve body in hopes that only one will fail with the other providing adequate protection.
Another approach has been to provide a solenoid coil which burns out and allows the valve to shut off if it is energized for more than a predetermined length of time. While these approaches offer solutions in some instances they do not solve the problems associated with valves that will not mechanically close because of contaminators in the supply system that prevent valve shut off, or in the case where the valve is functioning normally but the flooding condition is a result of a leak in the system.